Intervertebral fusion implant

ABSTRACT

The present invention provides an intervertebral implant for implantation in a treated area of an intervertebral space between vertebral bodies of a spine. The implant includes a spacer portion having an inferior and superior surface, wherein the inferior and superior surfaces each have a contact area capable of engaging with anatomy in the treated area, and the inferior and superior surfaces define a through-hole extending through the spacer body. The present invention further provides screw holes extending from a side portion to the inferior and superior surfaces of the spacer portion and a plate portion coupled to the spacer portion through a coupling means, wherein the plate portion contains screws holes for receiving screws. A screw back out prevention mechanism adapted on the plate portion and prevents the back out of screws from the screw holes.

FIELD OF THE INVENTION

The present disclosure generally relates to a fixation device forpositioning and immobilizing at least two adjacent vertebra. Inparticular, the present invention relates to a stand alone interbodyfusion device for implementation in the spine.

BACKGROUND OF THE INVENTION

The vertebrate spine is the axis of the skeleton on which all of thebody parts “hang”. In humans, the normal spine has seven cervical,twelve thoracic and five lumbar segments. The lumbar spine situs uponthe sacrum, which then attaches to the pelvis, and in turn is supportedby the hip and leg bones. The bony vertebral bodies of the spine areseparated by intervertebral discs, which act as joints but allow knowndegrees of flexion, extension, lateral bending, and axial rotation.

The typical vertebra has a thick anterior bone mass called the vertebralbody, with a neural (vertebral) arch that arises from the posteriorsurface of the vertebral body. The central of adjacent vertebrae aresupported by intervertebral discs. The spinal disc and/or vertebralbodies may be displaced or damaged due to trauma, disease, degenerativedefects, or wear over an extended period of time. One result of thisdisplacement or damage to a spinal disc or vertebral body may be chronicback pain. In many cases, to alleviate back pain from degenerated ofherniated discs, the disc is removed along with all or part of at leastone neighboring vertebrae and is replaced by an implant that promotesfusion of the remaining bony anatomy. However, the success or failure ofspinal fusion may depend upon several factors. For instance the spaceror implant or cage used to fill the space left by the removed disc andbony anatomy must be sufficiently strong to support the spine under awide range of loading conditions. The spacer should also be configuredso that it likely to remain in place once it has been positioned in thespine by the surgeon. Additionally the material used for the spacershould be biocompatible material and should have a configured thatpromotes bony ingrowth.

In combination with spacers or cages, a plating system is used tofurther stabilize the spine during the fusion process. These devices,commonly referred to as bone fixation plating systems, typically includeone or more plates and screws for aligning and holding vertebrae in afixed position with respect to one another. Plating systems independentof the spacers provide additional complications such as loosening andfailure of the hardware. Two common failures are the breakage of theplates, and the backing out of screws into soft tissues of the patient'sbody. The backing out of the screws is typically a result of the screwsfailure to achieve a sufficient purchase in the bone, although thestripping of the screws has also been known to cause this problem.

There is a need for a spine stabilization system that in promotes fusionof adjacent vertebrae while at the same time provides stabilization ofthe spinal area where fusion occurs. There is a need for a system thatincorporates both the fusion element and the plating element in onesystem to reduce the possible complications that may occur. There isalso a need to provide a system that reduces the complications that mayoccur in the fusion element and the plating element and to need for thissystem to be configured so that positioning this system is efficient andeasy.

SUMMARY OF THE INVENTION

The present invention provides an intervertebral implant forimplantation in a treated area of an intervertebral space betweenvertebral bodies of a spine. The implant includes a spacer portionhaving an inferior and superior surface, wherein the inferior andsuperior surfaces each have a contact area capable of engaging withanatomy in the treated area, and the inferior and superior surfacesdefine a through-hole extending through the spacer body. The presentinvention further provides screw holes extending from a side portion tothe inferior and superior surfaces of the spacer portion and a plateportion coupled to the spacer portion through a coupling means, whereinthe plate portion contains screws holes for receiving screws. A screwback out prevention mechanism adapted on the plate portion and preventsthe back out of screws from the screw holes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of an intervertebralimplant according to the present invention;

FIG. 2 is another perspective view of the embodiment of the implantshown in FIG. 1;

FIG. 3 is a side view of the intervertebral implant of FIG. 1;

FIG. 4 is a top view of the intervertebral implant of FIG. 1;

FIG. 5 is an exploded view of the intervertebral implant of FIG. 1;

FIGS. 6 and 7 is a perspective view of the intervertebral implant ofFIG. 1 which include illustrations of bone fasteners;

FIG. 8 is another side view of the intervertebral implant of FIG. 1incorporating bone fasteners;

FIG. 9 is a perspective view of another embodiment of the stand aloneintervertebral implant;

FIG. 10 is a front view of the intervertebral implant of FIG. 9;

FIG. 11 is a top view of the stand alone intervertebral implantillustrated in FIG. 9;

FIG. 12 is an exploded view of the stand alone intervertebral implant ofFIG. 9;

FIG. 13 is yet another embodiment of the stand alone intervertebralimplant;

FIG. 14-16 are different views of the stand alone intervertebral implantof FIG. 13; and

FIG. 17 is another embodiment of the implant of FIG. 14 according to thepresent invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Embodiments of the disclosure are generally directed to flexiblestabilization systems for use with the anterior, antero-lateral,lateral, and/or posterior portions of at least one motion segment unitof the spine. The systems of the invention are designed to beconformable to the spinal anatomy, so as to be generally less intrusiveto surrounding tissue and vasculature than existing rigid stabilizationsystems.

Certain embodiments may be used on the cervical, thoracic, lumbar,and/or sacral segments of the spine. For example, the size and massincrease of the vertebrae in the spine from the cervical to the lumbarportions is directly related to an increased capacity for supportinglarger loads. This increase in load bearing capacity, however, isparalleled by a decrease in flexibility and an increase insusceptibility to strain. When rigid immobilization systems are used inthe lumbar segment, the flexibility is decreased even further beyond thenatural motion restriction of that segment. Replacing the conventionalrigid immobilization systems with certain embodiments disclosed hereinmay generally restore a more natural movement and provide added supportto the strain-susceptible area.

FIGS. 1-8 illustrate the different views of one particular embodiment ofthe present invention. The intervertebral fusion implant as shown inFIGS. 1-8 is a stand-alone anterior lumbar interbody fusion device usedto provide structural stability in skeletally mature individualsfollowing discectomies. These implants are available in various heightsand geometric options to fit the anatomically needs of a wide variety ofpatients. Specifically, FIGS. 1-4 illustrate one embodiment of anintervertebral fusion implant 10 according to the present invention.Implant 10 is generally positioned in the intervertebral space betweentwo adjacent vertebrae. As shown in the figures, implant 10 primarilyincorporates a spacer portion 12 and a plate portion 14. In thisparticular embodiment, the spacer portion 12 includes a graft window 16for the placement of bone graft to enhance fusion between two adjacentvertebrae. The plate portion 14 includes at least one screw hole 18,however, in the preferred embodiment of the present invention, threescrew holes 18 are provided. Also, in the plate portion 14 of theimplant 10, a screw back out prevention mechanism 20 is provided. Thereis also provided a coupling means 22 which connect the spacer portion 12and the plate portion 14 rigidly to each other. The coupling means 22will be discussed in greater detail with reference to FIGS. 5-8.

The spacer portion 12 can be comprised of any material that is conduciveto the enhancement of fusion between the two adjacent vertebrae. In oneparticular embodiment, the spacer portion 12 is made of PEEK materialwhich is physiologically compatible. It should be noted that any othermaterial that are physiologically compatible may also be used. Thespacer portion 12 is made from radiolucent polymer in order to permitradiographic visualization. The spacer portion 12 further comprisessuperior and inferior portions that are provided with a plurality ofpyramidal protrusions 13. The superior and inferior portions of thespacer portion are bi-convex for greater contact with the vertebralendplates of the adjacent vertebrae. The protrusions 13 can beconfigured to be any size or shape for further anchoring the spacerportion 12 to each of the adjacent vertebrae. Protrusions 13 on thesuperior and inferior surfaces of each implant grip the endplates of theadjacent vertebrae to aid in expulsion resistance. The plate portion 14can also be comprised of any physiologically compatible material. In thepreferred embodiment, the plate portion of the implant 10 is composed oftitanium. The plate portion 14 as illustrated in FIG. 1, are providedwith three screw holes. However, it should be noted that implant 10 maybe comprised of only one screw hole. The screw holes 18 are situatedboth in the spacer portion 12 and the plate portion 14 for receivingbone screws which are attached to the adjacent vertebral bodies atdifferent angles.

FIG. 5 illustrates an exploded view of the intervertebral stand alongfusion device 10. In this exploded view, clearer view of the combinationof the plate portion 14 and the spacer portion 12 is illustrated. Thespacer portion 12 and the plate portion 14 are coupled to each otherview connection points 24 and through the use of connection pins 26 and28.

FIGS. 6-8 illustrate the fusion device 10 in various views associatedwith the screws 30 provided in pin holes 18. The pin holes 18 areconfigured to receive screws 30 at various angles. The screws 30 enterthe pin holes at specified angles to enter the adjacent vertebral bodiesat the optimal locations. The screws 30 are configured and adapted toprovide optical purchase with the adjacent vertebral bodies.

Now, turning to the method of positioning the implant, it should benoted that the intervertebral implant 10 is positioned in the spineafter the disc portion between two vertebral bodies is exposed andremoved using rongeurs and other suitable instruments. The posterior andlateral walls of the annulus are generally preserved to provideperipheral support for the implant and graft materials. A trial deviceattached to a trial holder is then inserted into the disc space todetermine size of the implant. This procedure is generally conductedusing fluoroscopy and tactile feel. After the appropriate sized implantis selected and attached to an implant holder and drill guide, theimplant may be inserted into the disc space. Once the implant ispositioned with the disc space, supplemental graft material can used toenhance fusion. Once the implant is positioned inside the disc, an awlor any similar type of instrument can be used to drill through the screwhole and break the cortex of the adjacent vertebral body. The surgeonperforming this procedure may then use a depth gauge to determine thescrew length. Once the appropriate screw length is determined, screwsare inserted using a self-retaining screwdriver. After the screws arefinally inserted and secure thereby providing solid purchase with theadjacent vertebral bodies, the screw anti back out mechanism is engagedand secure. In this particular embodiment, the anti back out mechanismis two set screws that retain the three screws with the implant.

FIG. 9 illustrates a perspective view of the stand alone intervertebralimplant 32 for positioning in the cervical region of the spine. Thepresent invention relates to an implant having a peek spacer portion 33that is coupled to a titanium plate portion 34 through the use oftitanium dowel pins. However, it should be noted that the titanium plateportion 34 and the peek spacer portion 33 maybe coupled through anyother feasible means such as hooks, screws, and any other type offastening means. The implant 32 also allows for at least two titaniumscrews 36 and 37 to be inserted at a compound angle for maximum screwpurchase into the superior and inferior vertebral bodies. A lockingmechanism 38 is provided on the plate portion 34 to capture the sides ofboth of the at least two screws 36 and 37 with a 90 degree turnpreventing the titanium screws 36 and 37 from backing out. It should benoted that the present application is not limited to being of a PEEKspacer and a titanium plate. Other materials that are physiologicallycompatible which are similar and which may be unique to spacers andplates may be utilized in various combinations.

FIGS. 10 and 11 illustrate the front view of the plate portion of theimplant. Specifically, FIGS. 10 and 11 illustrate an open and a closeposition with reference to the anti back out mechanism 38. Also, itshould be noted that the titanium plate 34 is provided with knife likeedges 35 which are designed to engage the vertebral body and providesadditional torsional stability to that of the bone screws. The plate 35is also provided with “eye brows” like structure which fully capturesthe bone screws 36 and 37 while still allowing for the screws to resideabout the tooth root plane and remaining lower than the tooth(protrusions on the spacer portion 33). The plate 35 geometry allows forthe minimum reduction of peek volume. The plate 35 height remains levelto the peek tooth root so that compressive loads are always subjected tothe peek body where the graft is contained. Compound holes are drilledto accept bone screws 36 and 37 and to allow for fixed or variable anglescrews. The anti back out mechanism is engaged so that the screws 26 and37 do not back out of the implant 32.

FIG. 12 illustrates an exploded view of the intervertebral implant. Theplate portion 34 and spacer portion 33 have at least 2 male and femaleledges which are capable of interfacing with each other. The connectionof the male and female ledges are offset at different heights tominimize cross-sectional area loss. Also illustrated in FIG. 12 is thedowel pins used to connect the spacer portion to the plate portion asone means of coupling of the spacer portion 33 and the plate portion 34.It should be noted that various means such as hooks, staples and screwscan be used to attach the spacer portion to the plate portion of thepresent invention.

The spacer portion 33 of the implant provides a leading edge chamferwhich enables self distraction of the vertebral bodies while inserting.The spacer portion 33 also provides teeth like structures in thesuperior and inferior aspects of the spacer body to help preventmigration of the implant. The root of the teeth or protrusions on thebase of the implant serves as the defining plane for the superior andinferior vertebral bodies. Finally, the spacer portion 33 provides anaxial shaped hole which enables a maximum amount of graft for packingwithin the implant. However, it should be noted that the graft hole canbe designed to be multiple holes or any in other geometrical shape toenhance fusion through the insertion of graft material.

FIGS. 13-16 illustrate a stand-alone fusion device for position in alateral approach. The stand-alone fusion device 40 consists of a spacerportion 42 and a plate potion 44. The spacer portion and the plateportion are configured to be able to receive screws 46 and 48 forattachment to adjacent vertebral bodies. The plate portion 44 isprovided with an anti back out mechanism 50 so that the screws 46 and 48are fixedly retained within the fusion device 40.

FIG. 17 illustrates another embodiment of a stand-alone intervertebralimplant 60 that is poisoned into the disc space laterally. In thisembodiment, which is similar to the embodiment disclosed in FIGS. 13-16,the spacer portion 62 is provided with a plurality of protrusions in thesuperior and inferior portions. These protrusions grip the endplates ofthe adjacent vertebrae to aid in expulsion resistance. The spacerportion 62 also contains a plate receiving area 63 for receiving theplate portion 64. The plate receiving area 62 is configured to receive aplate protrusion 66 for coupling the spacer portion 62 and the plateportion 63 together through the use of pins or any other similar type ofcoupling means.

The plate portion 64 is configured with at least two screw holes forreceiving screws 68. The screws 68 are positioned at angles to insertthrough the spacer and the adjacent vertebral body to gain maximumpurchase and stability. The screws 68 are retained with the implant 60through the use of an anti screw back out mechanism 70. When thismechanism is engaged by turning at least 90 degrees through the use aninstrument such as a screwdriver, the screws 68 are maintained withinthe implant and the boney structure of the adjacent vertebral bodies.

While it is apparent that the invention disclosed herein is wellcalculated to fulfill the objects stated above, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art.

What is claimed is:
 1. An intervertebral implant for implantation in atreated area of an intervertebral space between vertebral bodies of aspine, wherein said implant comprises: a spacer having, an inferior andsuperior surface, wherein the inferior and superior surfaces each have acontact area capable of engaging with anatomy in the treated area, andthe inferior and superior surfaces define a through-hole having an innersurface extending through the spacer; screw holes extending from a sideportion to the inferior and superior surfaces of the spacer; a platerigidly coupled to the spacer, wherein the plate contains screws holesfor receiving screws; and wherein a screw back out prevention mechanismadapted on the plate for preventing the back out of screws from thescrew holes, wherein at least two grooves and spaced apart about theentire inner surface of the spacer, wherein a tongue extends from thesuperior surface to the inferior surface of the spacer and into thethrough hole and does not extend the entire length of the through hole,and is configured with a radius at one end, wherein the screw back outprevention mechanism is two set screws that retain at least threescrews, wherein the plate comprises an extension that is adapted to matewith a connection groove on a anterior portion of the spacer, andwherein the plate is not moveable with respect to the spacer.
 2. Theintervertebral implant of claim 1, wherein the at least two screws areinserted into adjacent vertebral bodies at divergent angles.
 3. Theintervertebral implant of claim 1, wherein at least one pin rigidlycouples the spacer with the plate.
 4. The intervertebral implant ofclaim 1, wherein the plate and the spacer are configured to structurallymate with one another.
 5. The intervertebral implant of claim 1, whereinthe plate is comprised of metal.
 6. The intervertebral implant of claim1, wherein the at least one groove is configured circumferentially onthe inner surface of the spacer.
 7. The intervertebral implant of claim1, wherein the spacer is comprised of plastic.
 8. The intervertebralimplant of claim 1, wherein the spacer comprises a plurality ofprotrusions on superior and inferior surfaces of the spacer.
 9. Anintervertebral implant for implantation in a treated area of anintervertebral space between vertebral bodies of a spine, wherein saidimplant comprises: a spacer having an inferior and superior surface,wherein the inferior and superior surfaces each have a contact areacapable of engaging with anatomy in the treated area, and the inferiorand superior surfaces define a through-hole and an inner surfaceextending through the spacer; screw holes extending to the inferior andsuperior surfaces of the spacer; a plate rigidly coupled to the spacerportion through a coupling means, wherein the plate contains screwsholes for receiving screws; and a screw back out prevention mechanismadapted on the plate and prevents the back out of screws from the screwholes, wherein the plate comprises an extension that is adapted to matewith a connection groove on a anterior portion of the spacer, theextension extending an entire length of the plate and the connectiongroove extending the entire length of the anterior portion of thespacer, and wherein the plate is not moveable with respect to thespacer.
 10. The intervertebral implant of claim 9, wherein the at leasttwo screws are inserted into adjacent vertebral bodies at divergentangles.
 11. The intervertebral implant of claim 9, wherein the couplingmeans is at least one pin that rigidly couples the spacer portion andthe plate of the intervertebral implant.
 12. The intervertebral implantof claim 9, wherein the plate and the spacer are configured tostructural mate with one another.
 13. The intervertebral implant ofclaim 9, wherein the plate is comprised of metal.
 14. The intervertebralimplant of claim 9, wherein the spacer comprises a plurality ofprotrusions on the superior and inferior surfaces of the spacer.
 15. Animplant for positioning between adjacent intervertebral bodiescomprising: a spacer having an anterior portion, a posterior portion,first and second side portions, and superior and inferior surfaces; aplate having an anterior face and a posterior face, first and secondside portions, and superior and inferior surfaces; at least two throughholes extending from the anterior face of the plate through an anteriorportion of the spacer; at least two fasteners extending through theplate and the spacer and contacting the adjacent vertebral bodies;wherein the plate comprises an extension extending out from theposterior portion of the plate and extending the entire length of theplate, wherein the extension of the plate mates with a connection grooveof the spacer, the connection groove of the space configured on theanterior portion of the spacer and extending the entire length of thespacer, where connection pins couple the spacer to the plate so that theplate does not move with respect to the spacer.